Chlorogenic acid shows a wider antibacterial action, but can be inactivated in vivo by proteins. Analogous to caffeic acid, chlorogenic acid can improve the central excitation of rats by oral administration or intraperitoneal injection. Chlorogenic acid may intensify the small bowel peristalsis for rats and mice, and the uterus tension of rats. It shows choleretic effect, and can promote the bilification of rats. Chlorogenic acid has an allergization for human, and inhalation of the plants dust containing it may cause asthma, dermatitis and so on. At present, many isolation and purification methods of chlorogenic acid have been reported, such as the application number CN201010558366 entitled “the production method for preparation of chlorogenic acid by freezing, concentrating, crystallizing”. Said invention disclosed one production method of chlorogenic acid crystals, that belonged to a new method for the concentration of natural product extract solution, and during the process of isolation and purification of natural products, that can be used in the concentration of aqueous solution and in the crystal isolation of compounds. The inventors made 50% solution of chlorogenic acid in methanol crystallize at 0° C., filtered out crystals, and the crystal mother liquid was frozen at −50° C. Then, the obtained ice was taken out, and crushed into powder using ice flaker. The ice powder was subjected to centrifugal separation by a centrifugal separator, to produce the solution of chlorogenic acid in methanol at high concentration. Then, to the resulted solution, was added water, to obtain 50% solution of chlorogenic acid in methanol. This solution was placed at 0° C. to crystallize, and crystals were isolated and subjected to vacuum freeze-drying, to provide chlorogenic acid at a content of more than 98%. Application number CN201210543580 entitled “one method for the preparation of chlorogenic acid from leaves of Lonicerahypoglauca” disclosed one production technology of simultaneously extracting asperuloside and chlorogenic acid from leaves of Eucommia ulmoides. Dried Eucommia ulmoides leaves were used as raw materials, and purified asperuloside was produced by the following process technology: extracting with the aid of water bath heating, loading on the column, eluting, concentrating, dynamically extracting, crystallizing, recrystallizing, etc; after crystallizing, the acetone mother solution was further concentrated and combined with the thick paste from dynamic extraction, to extract chlorogenic acid. The application number CN201010135116 (entitled “one method for the preparation of purified chlorogenic acid from leaves of Eucommia ulmoide”) related to one method for the preparation of purified chlorogenic acid from leaves of Eucommia ulmoide and reported the process technology: extracting by macerating in deionized water at room temperature, pressing (or centrifuging), enriching by macroporous adsorption column chromatography, extracting with ethyl acetate, recrystallizing in deionized water.
General methods for purification of chlorogenic acid also include resin column chromatography, polyamide column chromatography, gel chromatography, high performance liquid chromatography, crystallization and recrystallization, etc. Resin column chromatography can enrich and purify chlorogenic acid, but this method cannot ensure that the purity of sample and impurities conform the requirements for medicine; polyamide column chromatography has an ability of well isolating chlorogenic acid and flavones, and leading to higher purity of chlorogenic acid, but the operation is trouble, the elution time is long, the cost is high, the materials are not easily regenerated, and the investment for industrialization is larger; gel chromatography can produce high purity of chlorogenic acid, but considering the high price and the low yield of products, it is hard for gel to be used in the industrial production; high performance liquid chromatography (HPLC) can provide high purity of chlorogenic acid, but due to high technical requirements and the low yield, HPLC is still in the laboratory stage; crystallization and recrystallization are a general purification method, and this method can enrich and purify chlorogenic acid, but one solvent is usually used for the purifying process of crystallization and recrystallization, and the impurity removed by this purification is rather special, thus it is almost impossible to perform a purification from impurities with different polarity. Crystallization and recrystallization show stronger selectivity for extracts, and cannot be widely used for all extracts prepared by different process. Some references have reported the purifying method of crystallization and recrystallization using combined solvents, and impurities with different polarity can be removed by adjusting the types and the ratios of combined solvents, realizing the object of purification. This method can get rid of impurities with different polarity in the extract, but because there are great difficulties in recovering solvent combinations, this method also has some limitations. Meanwhile, the combined solvents remain in products, that may bring a potential safety hazard.